Dual pump and fluid motor system

ABSTRACT

A dual pump and fluid motor system comprising two pumping chambers, two hydraulic cylinders with pistons, a reservoir and dual conduit means to communicate the reservoir to the pumping chambers and the pumping chambers to the cylinders. Suitable inlet and outlet check valves are positioned between the reservoir and the chambers and between the chambers and the cylinders respectively in each conduit. The check valves are normally in a position permitting simultaneous charging of both cylinders but may be selectively unseated by a single lever means to charge only one cylinder while holding the other in a fixed position, or to release both cylinders at the same time or to release one cylinder while charging the other.

United States Patent [151 3,635,595

Allard 1 Jan. 18, 172

54] DUAL PUMP AND FLUID MOTOR 2,439,796 4/1948 Dearsley ..417/427 SYSTEM [72] Inventor: Gordon H. Allard, Menomonee Falls, Wis.

[73] Assignee: Applied Power Industries, Inc., Milwaukee, Wis.

[22] Filed: Jan. 16, 1970 [21] Appl. No: 3,267

[52] U.S. Cl ..4l7/426, 222/385 [5 l 1 lnt. Cl ..F04b 23/04, 862d 5/40 [58] Field of Search ..4l7/238, 426, 427; 60/52 HA, 60/97 P; 222/385 [56] References Cited UNITED STATES PATENTS 2,214,257 9/1940 Pfauser ..60/52 HA X 2,286,880 6/l942 Traut ..60/52 l-lA Primary ExaminerRobert M. Walker AnorneyJohn J. Byme l ABSTRACT A dual pump and fluid motor system comprising two pumping chambers, two hydraulic cylinders with pistons, a reservoir and dual conduit means to communicate the reservoir to the pumping chambers and the pumping chambers to the cylinders. Suitable inlet and outlet check valves are positioned between the reservoir and the chambers and between the chambers and the cylinders respectively in each conduit. The check valves are nonnally in a position pennitting simultaneous charging of both cylinders but may be selectively unseated by a single lever means to charge only one cylinder while holding the other in a fixed position, or to release both cylinders at the same time or to release one cylinder while charging the other.

9 Claims, 4 Drawing Figures PATENTEU JAN? 8 I972 SHEET 1 OF 2 INVENTOR Gordon H Al/ard alessLsss PATENTEU JAN 1 8 I972 SHEET 2 BF 2 Fig. 2

A" III Hill my! Fig. 3

v INVENTOR Gordon H A/laro' DUAL PUMP AND FLUID MOTOR SYSTEM This invention relates broadly to a dual pump and fluid motor system and more specifically relates to a single leveroperated control valve for selectively charging and releasing a pair of single-acting cylinders which are in direct communication with a dual chamber pump.

In many multicylinder hydraulic systems it is normally necessary for one cylinder to be operated relative to the other when originating from a single pumping source. An important use for a multicylinder system having independent control for each cylinder is in leveling systems wherein one cylinder may be extended relative to another to level a platform or the like supported by the cylinders.

An important objective of this invention is to provide a control means for a dual pump and fluid motor system wherein a single handle is movable to a plurality of positions for selectively charging, holding, or releasing one or both of the operating cylinders.

It is a further object of this invention to provide a unitary means for controlling the flow of fluid from a reservoir through a pump to a plurality of cylinders in such a manner that one cylinder may be charged or released relative to the other without varying the displacement in the chambers of the pump connected to the individual cylinders or without inactivating the pump.

A preferred embodiment of this invention includes a housing having a dual chamber pump mounted thereon, a reservoir in communication with said pump chambers and two hydraulic cylinders, each in communication with one of said pump chambers. The respective chambers and cylinders and the reservoir are communicated through dual conduit means having inlet ball check valves in said dual conduits between said reservoir and the respective pumping chambers and outlet ball check valves in said dual conduits between the two cylinders and their respective pumping chambers. The ball check valves in their normal positions permit both cylinders to be charged simultaneously. A single-lever control means is mounted on said housing for pivotal movement in transverse planes and has a cam surface thereon which engages release shafts slidably extending into each of said conduits. Upon a specified pivotal movement of the lever, the ball check valves can be selectively unseated in a predetermined manner to (I) charge one cylinder relative while holding the other (2) release one cylinder while charging the other (3) release both cylinders simultaneously and (4) hold both cylinders in a fixed position though the pump continues its pumping action.

These and other objectives of the invention will be more fully understood upon reading the following specification taken in view of the drawings wherein,

FIG. I is a front view in elevation of the system of this inven tion, with portions broken away;

FIG. 2 is a view taken along lines 2--2 of FIG. 1',

FIG. 3 is a partial cross-sectional view of the embodiment shown in FIG. 2; and

FIG. 4 is a diagrammatic view of the various lever positions.

Referring now to the drawings wherein like numerals in dicate like parts, a pump generally indicated by the numeral is affixed to a housing 12. The pump includes cylinders 14 and 16 each having reciprocating plungers l8 and 20 slidably mounted therein. At their upper ends the plungers l8 and 20 are mounted to a beam pin 22 which pin is retained in openings formed in the upper ends of the plungers by means of retaining rings 24, 26. Mounted on the beam pin 22 between the two plungers is a beam 28 which receives a pumping handle, not shown. The beam is pivotally mounted at point 30 to link 32 which in turn is pivotally mounted to the housing at 34. Thepoint 30 serves as a fulcrum point upon suitable actuation of the pump handle to cause a reciprocation of the plungers l8 and 20 in the cylinders 14 and 16.

The housing further includes a reservoir 36 which has two dip tubes 38 and 40 which communicate with the two pump cylinders 16 and 14 respectively. The reservoir is communicated with the pumping chambers by dual conduit means. One of the conduits is shown in the cutaway view of FIG. 2.

The following description is in reference to the conduit shown in FIG. 2. It is to be understood that a conduit of identical construction and operation is provided on the other side for the cylinders 16. On the upstroke of the plunger in the cylinder 14, oil or other hydraulic fluid from the reservoir 36 passes upwardly through the dip tube 40 and through passageway 42 and unseats inlet ball check valve 44 which is mounted in the conduit between the reservoir and the pump cylinder 14. The fluid flows through passageway 46 into the pump chamber defined by the space left vacant by the up wardly moving plunger in pump cylinder 14. On the downward stroke of the plungers fluid is forced back through passageway 46 and unseats outlet ball check valve 48 which is normally biased to the closed position by spring 49. The fluid passes through the hollow set screw 50, used for adjusting the spring tension on the ball check valve 48, and through the outlet 52 to a single-acting cylinder, not shown, having a reciprocating piston therein. An identical outlet is provided for the other pump cylinder 16 and] communicates with another single-acting cylinder.

The ball check valves are unseated by operation of reciprocably mounted release pins 54 and 54a each extending into the conduits. The release shafts are part of a single-lever control means comprising a lever 56 having a cam surface 58 which engages the shafts. The release shafts 54 and 540 are mounted in bearings, one of which is shown in FIG. 2 and is in dicated by the numeral 60. A setscrew 54 holds the bearing 60 in position. A spring 62 normally holds the release shaft in a position out of contact with the ball check valves. A seal 66 is provided to prevent fluid leakage.

Referring now to FIG. 3, the lever 56 is mounted to the housing for pivotal movement in transverse planes. The handle 56 has a shaft 68 mounted thereon which extends into a bore 70 in the housing 12. The shaft is threaded to a retaining nut 72 in the interior of the bore 70. A sleeve 74 surrounds the shaft 68 and is held fixed in the bore 70 by means of a setscrew 76. The retaining nut 72 abuts the edge of the sleeve 74 and precludes outward axial movement of the shaft. The shaft 68 can rotate about its own axis within said sleeve 74. The lever 56 is mounted to the shaft by a pivot pin 78 for pivotal move ment about an axis transverse to the longitudinal axis of the shaft 68. Because of the rotational movement permitted the shaft 68 within the sleeve 74, the lever can also be pivoted about the longitudinal axis of the shaft 68.

In operation, when the release shaft 54 and lever 56 are in the position shown in FIG. 2, fluid will pass through dip tube 40 on the intake stroke of the pump to unseat the check valve 44 and flow into the pumping chamber. On the downstroke of the plunger, the fluid will unseat the outlet ball check valve 48, pass through the outlet 52, and charge a single-action cylinder, not shown. It is to be understood that the operation is identical for the other pumping chamber, check ball valves, and outlet not shown. If the lever 56 is pulled forward, release shaft 54 (and 54a) is actuated. mechanically unseating inlet ball check valve 44 allowing fluid to return to reservoir on the downstroke of the plunger. The fluid will be under insufl'lcient pressure to unseat the outlet ball check valve 48. In this position, the pump will continue pumping but the operating cylinders (not shown) will be held in fixed position since the fluid is sent back to the reservoir. Farther forward, the inlet ball check valves will contact and unseat the outlet ball check valves releasing the fluid in the cylinders for entry back into the reservoir.

When it is desired to charge one cylinder while holding the other, the lever 56 must be rotated about the axis of the shaft 68. The cam surface 58 is cut to a predetermined angle and will engage the release shaft on the side to which the lever is rotated leaving the release shaft on the other side unaffected and out of contact with the ball check valves. For example, referring to FIG. I, the lever is rotated to the left to the phantom position 80, the release shaft 54a but not 54 will be engaged and will unseat its respective inlet ball check valve so that while the pump continues to operate only the right-hand cylinder will be charged while the left-hand cylinder will be held in a static position. The check valves on the right-hand side are unaffected by their respective shaft 54.

Upon further movement of the lever to the left to a full movement of 40 from its normal position the thicker upper part of the cam surface 58 will cause a further inward movement of the release shaft 54a causing the respective inlet ball check valve to engage and unseat the outlet ball check valve causing a release of the fluid in the left-hand cylinder while the right-hand cylinder is still being charged.

The operation may better be understood by referring to FIG. 4 which shows diagrammatically the respective lever positions for accomplishing the above-stated results. In position A," the handle is in the upright position and, if the pump is operating, the chambers are being charged. If the lever is pulled forward to the 8" position, the pump may still be operating but since the inlet ball check valves are unseated by operation of the lever and release shafts, the pump will be pumping fluid back to the reservoir and the respective operating cylinders will assume a hold position. Upon full forward movement of the lever to the position C," all check valves are unseated and the fluid in the cylinders is released. If the lever is rotated to position D, the right-hand inlet ball check valve is unseated and the right-hand cylinder assumes a hold" position while the left-hand cylinder is charged. Movement to the E" position causes an unseating of both the inlet and outlet valves and permits a full release of the right-hand cylinder while the left-hand cylinder is being charged. The same result occurs when the lever is moved to the G and H positions except with a reversal of the cylinders effected.

The mechanism of this system can also be adapted for use in a double-acting cylinder with the respective check valves operating as a four-way valve permitting selective fluid flow through the inlet and outlet of a sole, double-acting cylinder.

1 claim: 1. A pumping system comprising, a pump having first and second pumping chambers, a reservoir, first and second operating cylinders, first and second pistons in said first and second cylinders, dual conduit means communicating said reservoir with said pumping chambers and said chambers with said cylinders,

inlet valve means in each of said conduit means between said reservoir and said first and second pumping chambers,

outlet valve means in each of said conduit means between said first and second pumping chambers and said cylinders,

and single-lever control means for operating said inlet and outlet valve means mounted for pivotal movement in transverse planes having at least a first position permitting the pump to pump fluid from the reservoir to both of said cylinders,'a second position permitting the pump to pump fluid to only one of said cylinders, a third position permitting the pump to pump fluid to only one of said cylinders while permitting fluid in the other cylinder to return to said reservoir, and a fourth position permitting fluid to return to said reservoir from both of said cylinders.

2. A pumping system as define in claim 1 and wherein said inlet valve means and said outlet valve means includes ball check valves with the pump unseating said .inlet ball check valves during its intake stroke and unseating said outlet ball check valves during its output stroke when said single lever control means is in its first position.

3. A pumping system as defined in claim 1 and wherein said single-lever control means includes a release shaft for each of said conduit means movable by said lever to unseat said inlet and outlet valve means, and said lever has a cam surface for selectively engaging said release shafts in a predetermined manner upon movement of said shaft in one of said planes.

4. A pumping system as defined in claim 3 wherein when said lever is in said second position one of said inlet ball check valves is held in an unseated position by its respective release shaft.

5. A pumping system as define in claim 3 wherein when said lever is in said third position one of said inlet ball check valves and one of said outlet ball check valves in one of said conduit means are held in the open position by the release shaft in said conduit means.

6. A pumping system as defined in claim 3 wherein when said lever is in said fourth position said inlet ball check valves and said outlet ball check valves in each conduit means are held in the open position by each of said release shafts.

7. A pumping system as defined in claim 3 and including a fifth position for said lever whereby the operating cylinder pistons are held in a fixed position while the pump continues to operate.

8. A pumping system as defined in claim 7 wherein, when said lever is in said fifth position the inlet ball check valves in each conduit are held in the open position by each of said release shafts.

9. A pumping system as defined in claim 5 wherein said one of said outlet ball check valves is held in said open position by direct engagement by said one of said inlet ball check valves. 

1. A pumping system comprising, a pump havIng first and second pumping chambers, a reservoir, first and second operating cylinders, first and second pistons in said first and second cylinders, dual conduit means communicating said reservoir with said pumping chambers and said chambers with said cylinders, inlet valve means in each of said conduit means between said reservoir and said first and second pumping chambers, outlet valve means in each of said conduit means between said first and second pumping chambers and said cylinders, and single-lever control means for operating said inlet and outlet valve means mounted for pivotal movement in transverse planes having at least a first position permitting the pump to pump fluid from the reservoir to both of said cylinders, a second position permitting the pump to pump fluid to only one of said cylinders, a third position permitting the pump to pump fluid to only one of said cylinders while permitting fluid in the other cylinder to return to said reservoir, and a fourth position permitting fluid to return to said reservoir from both of said cylinders.
 2. A pumping system as define in claim 1 and wherein said inlet valve means and said outlet valve means includes ball check valves with the pump unseating said inlet ball check valves during its intake stroke and unseating said outlet ball check valves during its output stroke when said single lever control means is in its first position.
 3. A pumping system as defined in claim 1 and wherein said single-lever control means includes a release shaft for each of said conduit means movable by said lever to unseat said inlet and outlet valve means, and said lever has a cam surface for selectively engaging said release shafts in a predetermined manner upon movement of said shaft in one of said planes.
 4. A pumping system as defined in claim 3 wherein when said lever is in said second position one of said inlet ball check valves is held in an unseated position by its respective release shaft.
 5. A pumping system as define in claim 3 wherein when said lever is in said third position one of said inlet ball check valves and one of said outlet ball check valves in one of said conduit means are held in the open position by the release shaft in said conduit means.
 6. A pumping system as defined in claim 3 wherein when said lever is in said fourth position said inlet ball check valves and said outlet ball check valves in each conduit means are held in the open position by each of said release shafts.
 7. A pumping system as defined in claim 3 and including a fifth position for said lever whereby the operating cylinder pistons are held in a fixed position while the pump continues to operate.
 8. A pumping system as defined in claim 7 wherein, when said lever is in said fifth position the inlet ball check valves in each conduit are held in the open position by each of said release shafts.
 9. A pumping system as defined in claim 5 wherein said one of said outlet ball check valves is held in said open position by direct engagement by said one of said inlet ball check valves. 